1. Field of the Invention
This disclosure relates generally to synchronization of signal generators, and, more specifically, to synchronization for multiple arbitrary waveform generators.
2. Description of the Prior Art
This disclosure relates generally to synchronization of signal generators, and, more specifically, to synchronization for multiple arbitrary waveform generators.
A conventional solution for synchronizing arbitrary waveform generator (AWG) outputs is to fan out a common clock and provide a trigger signal to all of the AWGs from an external source. This method has a disadvantage in that the startup phase relationship of the clocks between AWGs is random every time the clock is turned on or the frequency is changed. Also this requires the use of an oscilloscope and Arbitrary Function Generator (AFG) or user-provided clock and trigger source that meets the requirements.
In the conventional art, the alignment between instruments is currently a three-step process:
First, the instruments are set up with a common reference or external clock and the sample rate is set.
Next, to start waveforms at the same time, the two AWGs can be triggered with a common external trigger. The AWGs are set to synchronous trigger mode, which starts a waveform output on a divided clock edge rather than a sample clock edge. This provides wider setup and hold window trigger timing. The trigger mode must be synchronous with the internal divided clock for synchronizing AWGs and the trigger is provided from an external source like an AFG or customer provided clock signal. Each AWG is setup to start playing output waveforms when a trigger is received.
Finally, when the two AWGs start up, the internal divided clocks start with a random phase relative to one another. As a result, the outputs need to be aligned each time the sample rate is changed or the clock is stopped. In addition, there is timing skew from this divided clock to the output that is unique to each instrument.
Alignment is accomplished by observing the output signal or marker from each AWG and adjusting the clock phase until they line up. This is where there is an element of random chance in the setup. If the initial startup is too far out of alignment, for example greater than 2 ns, then there will not be enough range to adjust the phase of one AWG to line up with the other. In this case one needs to change the clock and change it back to start up in a different phase and restart the system with a common trigger sent again and the skew between the outputs is check again to see if within adjustment range.
It is therefore desired to enable synchronization in multi-AWG systems that better addresses these and other limitations of the prior art.